Telephone system and apparatus.



A, K; ANDRIANO. TELEPHONE SYSTEM AND APPARATUS. APPLICATION FILED JULY3. 1909.

3 BHBETS-SHEET l.

witnesses 20 0 attesting Patentefii May 17, 1910.

A. K. ANDRIANO.

TELEPHONE SYSTEM AND APPARATUS APPLICATION FILED JULY 3. 1909.

58,0670 Patented May 17, 1916.

3 SHEETS-SHEET 2.

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ANDREW a GRAHAM c0w PMOTO-UTHOGRAPHiRS. WASHINGTON, a. a

A. K. ANDRIANO. TELEPHONE SYSTEM AND APPARATUS.

APPLICATION FILED JULY 3, 1909.

Patented May 17, 1910.

3 SHEETS-SHEET 3,

M N MQ ES Em ANDEEw a. GRAHAM 00.. vuoTaumoGRAPuERs,ymsummou. n c

TINTT riar earner orricia ALBERT KOCH ANDBIANO, OF SAN FRANCISCO,CALIFORNIA, ASSIGNOR T0 DIRECT- LINE GENERAL TELEPHONE COMPANY, OF SANFRANCISCO, CALIFORNIA, A COR- PORATION OF CALIFORNIA.

TELEPHONE SYSTEM AND APPARATUS.

To all whom it may concern:

Be it known that I, ALBERT Koorr Annm- ANO, a citizen of the UnitedStates, residing in the city and county of San Francisco and State ofCalifornia, have invented new and useful Improvements in TelephoneSystems and Apparatus, of which the following is a specification.

This invention relates to improvements upon switching devices andcircuit-controllingmeans for telephone systems of which the devices andmechanism shown and described in the Letters Patent of the UnitedStates, No. 692,189 granted to me on January 2S, 1902 may be taken asthe type or class.

The improvements are applicable more particularly, therefore, to whatare included under the general term of interconnecting or direct-linetelephone systems, wherein each station or telephone is furnished withmeans for making connection with and calling up any other station ortelephone without going through a central station, thereby dispensingwith the services of an operator and the connections required in acentral station system.

The general object of these improvements is to more effectively insurethe privacy of the line completed for talking between two stations ortelephones at the time of use, and especially to prevent a person at athird telephone from switching his receiving circuit on to a linealready in use and overbearing the conversation unknown to the partiesusing the line. And with this end in view the invention comprises novelmeans of controlling the switch by the movement of the ringing-key aswell as the arm of the telephone-hook, the parts being arranged so as tooperate in such manner that after the switch has been set it will belocked by the act of calling up another station and its position cannotbe changed after the signal has been sent in until the telephone isdisconnected by hanging up the receiver.

The invention includes, secondly, a novel construction ofcircuit-controlling means in combination with the local circuit of thereceiving and transmitting instruments, where- Specification of LettersPatent.

Application filed July 3, 1909.

Patented May 17, 1910.

Serial No. 505,877.

the movable-member of the switch is moved from its normal position ofrest on its own line, but, through the operation of ringing up anotherstation the circuit, is put in condition for talking with the stationbeing rung up.

In both of these points or features the present improvements areespecially applicable to the switching-circuit controlling meansembraced in the Letters Patent No. 692,189 above referred to. Themovablemember of the switch in that patent is so controlled by lockingdevices that it cannot be moved until the receiver is first taken offthe hook. When that is done, the switch can be set to the line ofanother station; but after being thus set to one line, it is possible tomove the switch in that patent forward from one contact point toanother; because in the locking means that are brought into play bytaking down the receiver no provision is made for preventing themovablemember of the switch from being moved in a forward direction andset to another line, although it cannot move back to its ownline-contact until the receiver is hung up.

The switching device in the present invention is controlled againstreturn movement in the same manner, and is movable in a forwarddirection from point to point in the switch at any time before ringing,after the receiver is taken from the hook. But when the ringing-key ispressed to call the station at the other end, the switch is instantlylocked and remains where it was set before the ringing-key was pressed.From that position it can be moved only by returning the receiver to thehook; by which operation the switch is automatically returned to andlocked on its own line-contact, and it cannot be moved again until thereceiver is taken off its hook. The effect of this additional lockingmeans is to prevent a party from moving his switch to another line afterhe has closed the break in his local circuit, by going through theoperation of switching to and ringing up a station.

The locking-out means which is embraced in the second feature of thepresent invention, comprising circuit-closing contacts ar- -by thecircuit is broken on the instant that 1 ranged in the pillar of thetelephone-support or stand, electrically actuated means in cluding anelectro-magnet connectible in the ringing-circuit through theringing-key of the instrument, and mechanically operated circuit openingmeans through which the movement of the telephone-hook under the weightof the receiver, as the latter is placed on the hook, opens the circuitpreviously closed by the act of ringing up another station; these partsof the present improvements being constructed with a view to place themin the pillar of the stand and thus reduce the size of the base in whichthey have heretofore been placed.

The preferred embodiment of my improvements is explained at length inthe following description and is illustrated in the accompanyingdrawings in which Figure 1 is a topview of those parts of theswitching-mechanism and circuit-controlling devices that are situated inthe base of the telephone support and switch stand, the connectionblocks and wires being omitted, and some of the upper works such as thehead of the ringing-key being removed. Fig. 2 is a plan or top-view ofthe mechanism that moves and controls the switch, showing thebottom-plate of the frame with the top-plate removed. Fig. 3 is adetail, in perspective, of the parts through which the movement of theringing key is made to lock the switch. Fig. 4 is an elevation of thoseparts of the mechanism which are located in the pillar of the stand,showing the pillar in longitudinal section. Fig. 5 is a side-view on anenlarged scale of the circuit-closing contacts and the electromagnetremoved fromthe pillar. Fig. 6 is an elevation of the same parts takenfrom the left side of Fig. 5. Fig. 7 is a detail of the slide-plate thatoperates the rockingpiece of the locking-device. Fig. 8 is a diagram ofthe internal or local circuits of the instrument, including thetransmitter and receiver, the talking battery and the ringing-key. Fig.9 is a diagram illustrating the local circuits of three stations in thesystem and the connecting lines and common ringing circuit. This diagramrepresents station No. 1 connected for calling up and talking withstation No. 2.

The principal parts of the switch consist of the contact-points a atwhich the lines of different stations terminate in the base of thestand; the movable-member Z) the spindle (Z connected to themovable-member by a spur gear 6 and a pinion f, and the two looselypivoted dogs g, It. One of these dogs, 9, by engaging the teeth of thegear 6 holds the movable-member Z) from turning backward under thereaction of the spiral spring 10, but does not prevent the switch frombeing moved in a forward direction from one contact to another after thereceiver has been removed from the hook. The other dog it,

operates to engage the spur-gear and thereby lock the switch as long asthe receiver is left on the hook. It will be seen that these parts intheir general arrangement and operation do not differ from the lockingde vices in the Letters Patent No. 692,189, already referred to, but asthey are required to be shown in connection with the present novelfeatures, it is necessary to describe the general construction of themechanism for setting the two dogs g, it alternately 111 and out ofaction.

As heretofore constructed, the movablemember Z) of the switch could beset forward after being unlocked by taking the receiver from the hook;and except that it could not turn backward, there was nothing to preventa party after having switched to and called up one station, fromswitchmg from one line to another until he found the line that was beingused and on which he desired to listen.

In the present invention the switch is positively locked wherever it maybe set, on the instant that the ringing-key is pressed for the purposeof calling up the other station and no further adjustment of the switchis possible until it is first set back to its own line-contact byhanging up the receiver, and is afterward released for switching againby taking down the receiver. This additional lock consists of a dog 20movable in an are 011 a pivot 19 on the frame with its point in closerelation to, and held normally away from, the teeth of the gear 0, bythe movablecontact or stop 26 of the ringing-key, through the medium ofa swinging-plate 21 and a latch-piece 22. This last-named piece ispivotally attached to the swinging-plate, and is provided on one endwith an upwardlyturned catch 24, which by engaging a notch 25 in theside of the movable-stop 26 holds the swinging-plate stationary againstthe pulling force of a coil-spring 30 attached to the opposite end ofthe latch-piece, the other end of the spring being made fast to a fixedpoint on the frame behind the swingingplate.

A pin 29 fixed in the do 20 and extending upward through an opening inthe top-plate '2) of the frame, and also through a slot 28 in theswinging-plate 21, connects the dog with the latter piece; and the slotbeing inclined with reference to the curve in which the plate moves onits pivot 27, the effect of its throw in one direction is to set thepoint of the dog 20 into the teeth of the gear, and in the oppositedirection to disengage the dog from the gear. On one side of theswinging-plate an upwardly bent foot 31 with an angular edge 32 extendsunder one end of the vertically movable slide-plate m and when setacross the path of that piece is forced back by the downward movement ofthe slide-plate m under the weight of the receiver.

The movement of the swinging-plate 21 in the direction required to throwoff the dog 20 is thus efiected by hanging the receiver on its hook, andthe contrary movement to lock the gear is produced by a spring 30.

WVhile the receiver is on the hook the plate 21 holds the dog 20 awayfrom the gear, and in that position the plate 21 is retained by thelatch-piece 22, which holds the plate against the reactive force of thespring 30 by catching in the notch 25 on the movable stop 26. This holdsthe lock off the gear until the ringing-key 34 is depressed. The pullingforce of the spring 30 being applied diagonally to the latch-piece holdsthe catch 24 of that piece against the edge of the stop 26, so that theformer is released by pressing down the stop below the head of thecatch, and when allowed to rise the stop returns to position in linewith the catch, causing the latter to drop into the notch 25 as theplate 21 is again moved to the left. By virtue of this construction itwill be seen that the lock 20 is set ready for action whenever thereceiver is hung up and is left on the hook, and the lock beingcontrolled from the movablestop of the ringing-key, the lock is throwninto action by the movement of the stop in ringing up. When that step inthe operation of making connection with another station takes place theswitch is positively locked against moving forward as well as backward,and it cannot be set to the line of any other station until the motionsof returning the receiver to place and afterward taking it down tounlock the switch are carried out.

The improvements in the electrically-actuated means for controlling thecircuit of the instrument will be described with reference moreparticularly to the detail Figs. 4, 5, 6 and 7, and the diagrams, Figs.8 and 9. The circuit closing springs 17 and 18 together with the magnet14 and armature-piece 15 are situated in the pillar s of the stand inwhich sufficient space is provided to contain the parts and also affordroom for running the wires from the switch and connections in the baseof the stand to the magnet and the transmitter and receiver above; thelastnamed parts of the instrument being of wellknown form are notparticularly described and shown.

The windings of the spools of the magnet 14 are connected into the localcircuit through the movable-member b of the switch by a wire 48 carriedfrom one side of the windings to the front-stop 26 of the ringingkey.The armature-piece 15 carries an insulated contact-strip 15 that servesto connect the two contact-springs 17, 18 when the armature piece isattracted to the magnet.

The length of the armature-piece from the pivot 16 to the contactstrip15 being somewhat greater than the shortest distance between the pivotand the free ends of the circuit-closing springs 17 18, thearmaturepiece will be held in position by the pressure of the parts 1718 against the front edge of the contact-strip as often as it is drawnup and it will be held up by the springs 17, 18 after the circuit isopened through the magnet. As often as a current is passed through themagnet, which takes place when a circuit is completed for ringinganother station and the ringing-key is pressed, the strip 15 is broughtagainst the contact-springs 17, 18, and the break in the circuit at thatpoint remains closed as long as the armature-piece is retained in thatposition. The movements of the contact-strip are controlled through thearm t of the telephone-hook in such manner that the receiver must beremoved from the hook before the armature-piece can rise, and onreturning the receiver to place after use the contact 15 if previouslydrawn up by the magnet, will be mechanically separated from the springs17, 18. This is done by the same movement of the push-rod 12 thatoperates the slide m of the switchlocking means.

The rod 12 being attached by a loose joint 13 to the arm 25 of thetelephone-hook extends downward through the pillar to the verticallymovable slide-plate m, n, on which its lower end rests. A pin 12projecting from one side of the rod above the armaturepiece preventsthat piece from rising, while the weight of the receiver holds down thehook, and also presses the ar1naturepiece away from the contact-springs17, 18 whenever the receiver is returned to olace.

The circuit-closing springs 1r, 18 are interposed in the local circuitof the instrument between the induction coil I and the transmitter T,and in the arrangement of the wires and connections shown in the diagramFig. 8 the contact 18 is the terminal of a conductor 46 having the otherend terminating at the movable-member Z) of the switch, the transmitterT being situated between these two points. The other spring 17 is theterminal of a conductor 45 leading to the induction coil and in which issituated the circuit-closing contacts 39-41 that are commonly providedin these instruments to hold open the local talking circuit while theinstrument is not in use, and to close the circuit when the receiver isremoved for use. The break in the circuit at the points 39, 41

is closed, therefore, by the act of taking the 1 receiver off the hook,but upon moving the movable contact Z) from the contact (6*, individualto the station, to any one of the contacts a the circuit is broken at35, 36 and, being open at the contacts 17, 18, remains broken at thispoint until the magnet 14 can be brought into circuit with the ringingbattery.

An insulated circuit-closing piece 53 carried by the slide m, connectsthe two springs,

39, 41, when the slide is allowed to rise, but moves from between themleaving the circuit open at this point when the slide is held down bythe rod. Other contacts, 410, 42, which are also opened and closed bythe movements of the slide m, a, and the circuitclosing piece 53, but ina contrary order or sequence to that described for the contacts 39, &1,control the bell-circuit in the well known way, that is, by closing thecircuit through the bell B of the station while the receiver is on thehook, and opening it to cut out the bell whenever the receiver isremoved for use. In the present arrangement of the circuit andconnections this is required to be done before the switch can be set,and consequently the first movement of the parts as the receiver istaken from the hook is to close the local-battery circuit at thecontacts 39, 4-1 and open the bell-circuit at 40, 42. The switch maythen be moved to connect the local circuit of the station with the lineof another selected station, the movable-member 6 being set off itsownline-contact a to the proper one of the remaining contacts a intheswitch for giving the required connection. The station at theopposite end of the selected line will be in condition for being calledand for completing the circuit through both sets of trans mitters andreceivers for talking, provided the selected station is not already inuse, and if its switch Z) is standing on its own line-contact. Under allother conditions the circuit that includes the primary of theinduction-coil will be open at the contacts 17, 18, although it may beclosed at 39, ll by the receiver being off the hook. And as the circuitmust be closed either at or around the breaking point 1'7, 18 at thecalled station, as well as at the station from which the switching andringing is being done,

before the same is in condition for use, an additional set ofcontact-springs 35, 36, set in such relation to the movable-member ofthe switch I) that they will be in metallic contact or connection whilethe switch 6 is on its own line-contact a constitutes a supplementarycircuit-controlling means that bridges the breaking-point 17, 18 as longas the switch is left undisturbed, and leaves the circuit broken oropen. at the contacts 17, 18 when the switch is moved away from its ownline. The contacts 35, 36 are connected into the conductors 45, 416around the breaking-point 1T, 18, by the connections 50, 51, and are inmetallic contact with a circuitclosing piece 38 on the switch Z) butinsulated from it. The operation of these improvements will beunderstood by referring to the diagram Fig. 9 which illustrates thecircuits and connections of the instruments at three stations 111 asystem, and also the direct and return hnes and a commonringing-battery.

local battery G is placed on the line outside the contact (4*, and thereceiver R is arranged in closed circuit with the secondary of theinduction-coil I. The bell B is permanently connected by the wire 47into one side of the ringing-battery circuit H, and by the Wire 17 intothe line individual to the station. One stop of the ringing-key isconnected with the movable-member b of the switch and in that connectionis located the circuitclosing magnet 14, while the other stopis-connected directly in the circuit H of the ringing-battery. Underthis arrangement a circuit for ringing up one station from another, asstation N o. 2 from station No. 1 in the diagram Fig. 9, for example,will be traced as follows: From the ringingbattery M over the line H andconnection 47 to the bell B at station No. 2, thence by the conductor17, through the contacts 40, 12,

and over the connections 13, 43 to the line L individual to station N o.2, with the terminal aof which at station No. 1 the movable-contact orswitch 6 has been moved into engagement. From the switch the circuit iscontinued through connections designated 18 18, which include theelectro-magnet 14, to the ringing-key which, when the movablememberthereof is pressed, closes the break in the circuit at this point, thecircuit continuing thence by the wire 49 to the line H, leading back tothe ringing-battery. As the magnet 14- at station No. 1 is included inthis circuit, it will be seen that the local circuit of thecalling-station is closed at the break ing-point 17, 18011 the instantthat the ring ing-key is pressed, and the instruments are properlyconnected at both stations. The talking-circuit thus completed betweenthe two stations includes only the battery G on the line of station No.2, which supplies the necessary current for both induction-coils, as thecorresponding battery at the callingstation is cut out when'the switchZ) is moved away from its linecontact ta The talking-circuit between thetwo stations will be traced from the battery G at station No. 2 to theline-contact a individual to that station, and the switch 6 restingthereon, over "the conductor 16 to the transmitter T, over theconductors a6 and 51, contacts 35 and 36 bridged by the circuit-closingpiece 38, the conductors 50 and 45, and through the contacts39 and 41 tothe primary windings of the inductioncoil at station No. 2, which isconnected by the conductor n with the return line P. The primarywindings of the induction-coil at station No. 1, are likewise connectedwith the return line, and from this point the circuit may be furthertraced over the conductor 45, through the contacts 41, 89, closed by theconnecting piece 53, over the conductor 45 to the contact 17, thencealong the circuit closer 15 to the other contact 18, over the conductor46 to the transmitter, thence by the conductor 46 to the movable member6 of the switch that rests upon the contact a of line L individual tostation No. 2, and by it back to the battery G, at station No. 2, thuscompleting the circuit, which remains closed until the receivers arereturned to their hooks, by which operation the movable-member of theswitch at the calling station is caused to return to its own linecircuit, and the parts restored to normal conditions of rest with thecircuit again open at the contacts 17, 18 and closed at contacts 35 and36 at station No. 1.

What I claim as my invention and desire to secure by Letters Patentis 1. In a telephone switch a plurality of line-contacts, amovable-contact, locking de vices therefor, a movable support for thetelephone instrument when not in use, means operatively connecting thelocking devices with the telephonesupport to lock the movable-contactwhen the telephone is hung on the support and to unlock the said contactwhen it is returned to place, a ringing-key, a supplementarylocking-device, means operatively connecting it with the ringing-key tobring the same into action when the ringingkey is pressed, and means tothrow oflt the supplementary locking-device by the act of returning thetelephone instrument to place after use.

2. In a telephone switch, a plurality of line-contacts, a movablecontact, locking-devices therefor, means operatively connecting saidlocking-devices with the users telephone hook whereby themovable-contact is locked when the telephone is hung up and is releasedfor use by the act of taking down the telephone, a supplementarylocking-device and controlling means connecting the same with the usersringing-key and operating to bring the said locking-device into actionto lock the movable-contact when the ringing operation takes place, andmeans operatively connecting said controlling means with thetelephone-hook to throw off said supplementary look when the telephoneis hung up.

3. In a telephone switch, a plurality of line-contacts, amovable-contact, means for setting and holding the movable contact toany selected one of the line-contacts, a spring to return themovable-contact, a ringingkey, a locking device actuated by the movementof the ringing-key to lock the movable-contact, whereby the switchcannot be moved after the ringing-key has been pressed, and meansoperatively connecting the lockmg-device with the users telephone-hookto throw off the lock by the act of hanging up the telephone.

4. In a telephone switch having a plurality of line-contacts, amovable-contact, means -for setting and holding the movable-contact tomake a switch, and spring-actuated means for returning themovable-contact to its normal position when released; the combination ofa locking-device for the movablecontact, means operated by the usersringing-key to throw on the locking-device when the ringing-key isoperated, and means operatively connecting the switch-locking devicewith the users telephone-hook whereby the movable-contact is releasedand returned to position by the return of the telephone to the hook.

5. In a telephone switchingmechanism, a plurality of line-contacts, amovable-contact adjustable to any selected one of the linecontacts, asetting spindle to which the movable contact is connected by gears, aspring to return the movable-contact to normal position, a detentengaging the setting gears to hold the movable-contact against thereactive lorce of the spring, a locking-device holding themovable-contact normally locked, controlling means connecting saidlocking device with the users telephonehook, whereby the said lock isset off and the movable-contact is released for operation by removingthe telephone from the hook, a ringing-key, a second locking-devicenormally held out of action by the ringing-key, a spring-actuated meansfor throwing the last-named locking device on the movablecontact by theact of pressing the ringingkey, and means operated by the movement ofthe telephone-hook on hanging up the telephone to reset the secondlocking-device for action.

6. In a telephone switching-mechanism, the combination with a pluralityof linecontacts and means adapted by adjustment to connect thetalking-circuit of the station with another selected station through thelinecontact individual thereto of a ringingcircuit, including a mainbattery and a ringing-key and a signal at each station, means adapted bythe movements of the movablecontact in making a switch to complete theringing-circuit over the line connecting the calling station with thestation being called,

. a circuit-closing spring in the local circuit of the station betweenits switch and the transmitting telephone adapted to hold the saidcircuit open, an electro-magnet in the ringing-circuit between the mainbattery and the ringing-key of the station, a circuit-closing armaturethereto situated with relation to the circuit-closing springs to be heldin contact therewith by the resilience of the springs andmechanically-actuated means connected with the users telephone-hook toseparate the armature and the circuit-closing springs by the movement ofthe hook when the telephone is returned to place.

7. In a telephone switching-mechanism, the combination with thecircuit-closing contact-springs, of an electro-magnet in open circuitwith a battery, a circuit-closing key, an armature-piece pivotallyattached at one end to a fixed support, and having a contactstrip on thefree end to engage the said contact-springs under the attraction of thearmature-piece by the magnet, the contactstrip being so arranged withrelation to the said springs that they act to retain the contact-stripin position to close the circuit when the armature is attracted by themag net, and means for separating the contactstrip from the springscomprising the pivoted-arm, the push-rod, the stop on the rod, and aspring for raising the rod.

8. In a telephone system, the combination of a plurality ofline-contacts, means arranged to be set into engagement with any onethereof, a locking device for holding the said means positively upon theline-contact to which it may be set, means arranged to bring the saidlocking device into operation when a call is given, and means forreleasing the locking device when the telephone instrument is restoredto place after use.

9. In a telephone system comprising line wires and a calling circuitwith circuit-closing devices in the latter at the stations, thecombination of a plurality of line-contacts, means arranged to be setinto engagement with any selected one thereof, a lock for positivelyholding the said means upon the linecontact to which it may be set, andmeans arranged to hold the said lock in releasing position, comprisingparts operating when the telephone instrument is hung up and at rest,and other parts operated from the local circuit-closing device of thecalling circuit.

10. In a telephone system, the combination of a connecting switchcomprising a plurality of line-contacts, and means arranged to be setinto engagement with any selected one thereof, a local circuit at thestation including the telephone instruments, at circuit-closercontrolled by the movable elements of the connecting switch and arrangedto close a break in the local circuit when connection is made with theline-contact of its individual station but to open the circuit whenconnection is made with another line-contact, and means for closing thesaid break in the local circuit whenever a call is given.

11. In a telephone system, the combina tion of a connecting switchcomprising a plurality of stationary line-contacts, and means arrangedto be set into engagement with any selected line-contact, a localcircuit at the station including the telephone instruments, acircuit-closer arranged to close a break in the local circuit whenconnection is made with the line-contact of its individual station, butto open the circuit when connection is made with another contact, andelectro magnetically operated means for closing the said break in thelocal circuit whenever a call is given.

12. In a telephone system comprising a plurality of lines betweenstations and a calling circuit with means at each local station forgiving a call, the combination of a selecting switch comprising a seriesof linecontacts and means arranged to be set into engagement with anyselected line-contact, a local circuit at the station including thetelephone instruments, acircuit-closer controlling a break in the localcircuit, an electro-magnet for controlling the circuit-closer, situatedin the calling circuit and arranged to cause the break in the localcircuit to be closed when a call is given, and means for maintaining thecircuit-closer in position to close the brake after the call is givenand the electro-rnagnet has become deenergized.

13. In a telephone system comprising a plurality of lines betweenstations and a calling circuit with means at each local station forgiving a call, the combination of a selecting switch comprising a seriesof linecontacts and means arranged to be set into engagement with anyselected line-contact, a local circuit at the station including thetelephone instruments, a circuit-closer controlling a break in the localcircuit, an electro-magnet for controlling the circuitcloser, situatedin the calling circuit and arranged to cause the break in the localcircuit to be closed when a call is given, means for maintaining thecircuit-closer in position to close the break after the call is givenand the electro-magnet has become deenergized, and means for moving thecircuit-closer to open the local circuit, operated when the telephoneinstrument is hung up.

I l. In a telephone system comprising a plurality of lines betweenstations and a calling circuit with means at each station for giving acall, the combination of a selecting switch comprising a series oflinecontacts and means arranged to be set intoengagement with anyselected line-contact, a local circuit at the station including thetelephone instruments, in which circuit are two breaks, a circuit-closercontrolling one break in the local circuit arranged to close the circuitwhenever connection is made with the line-contact individual to thatstation but to open the circuit whenever connection is made with anotherline, another circuitcloser controlling the other break in the be closedthereloy and means for holding the local circuit arranged to normallyleave the last said circuit-closer in closing position break open, anelectro-magnet controlling after the magnet has ceased to act thereupon.10

the last said circuit-closer, situated in the ALBERT KOCH ANDRIANO.calling circuit and arranged When a call is Witnesses: sent from thelocal station to attract the said CHAS. W. SMITH,

circuit-closer and cause the local circuit to BRADFORD DONNELY.

